Amazon Interview Experience | On-Campus 2021

The whole process consisted of one coding round and 3 interview rounds. Due to covid, the whole process was virtual. 

Online Coding Round: It was conducted on AMCAT and it had 5 sections. 

• A debugging section, coding questions, feedback, aptitude, and personality assessment. 
• One had attempt both the coding questions, all debugging questions, and all aptitude questions correctly in order to get shortlisted.

Round 1: The interviewer was a straight-to-the-business man. And started the interview without introduction. 

• He first asked about this question: https://leetcode.com/problems/majority-element-ii/. I gave a brute force solution first, to which he asked TC and SC. He then asked to optimize it. I then explained  Moore’s Voting Algorithm. He was satisfied with my approach but didn’t ask me to code it. 
• He then moved on to ask questions on sorting algos. He asked about the best case and worst case TC of quick sort. Then he asked me to code it. 
• Further, he asked me to implement merge sort. During implementation, he changed the data structure from array to linked list, and asked me to write code for it. As we were running short on time, he told me to stop coding, and started rapid firing questions on TC of merge sort in various scenarios. This went on for about 10 mins. 
• In the end, he asked if I have any questions. We must ask genuine questions, which show our interest in the company. He then wished me luck for further rounds.

Round 2: This time too, the interviewer didn’t waste time and straight away gave me a problem. 

• It was basically a problem of graphs, where each node is a string of a given array. And, we had to use DSU to solve it. I told my approach and coded it efficiently.  He was really impressed and gave me another problem immediately. 
• It was https://www.geeksforgeeks.org/search-in-row-wise-and-column-wise-sorted-matrix/. I first gave a brute force solution of O(nm). He told me to optimize it, then I gave him a binary search solution of O(nlogn) TC. Still he, told me to further optimize it. I wasn’t able to come up with a solution, so he provided a hint. The optimal solution immediately clicked and I told it to him. He was quite satisfied and wished me luck for next round.

Round 3: The interviewer was an experienced guy with over 15 years spent in amazon. 

• He asked me to introduce myself, and give a brief overview of my projects. 
• He asked me to share my screen and open the project, as I hadn’t deployed it. 
• He asked about the implementation of various features and why had I added them. He just wanted to assess how do I handle new projects. 
• He then moved on to OS questions and started with deadlock. He asked me about various ways to prevent a deadlock, and how does Windows do it. The discussion further went on to scheduling algos. 
• Post this, he asked me this question https://www.geeksforgeeks.org/largest-sum-contiguous-subarray/. I started with brute force, and finally gave the optimal Kadane’s algo. He was satisfied with my explanation. 
• He then asked if I had any questions for him. I asked about his experience so far with Amazon. He happily explained it for about 5 mins. He then told me that you’ll enjoy working at Amazon. This gave me a strong hunch that I’m selected.

After 1 hour the results were announced and 9 were given the offer including me. I rejected it because I had another offer from Zomato and decided to go with that.